7,351 research outputs found

    Grounding Into a Double Standard: Understanding and Repealing the Curt Flood Act

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    This note calls for an end to Major League Baseball\u27s statutory exemption from antitrust law for acts that are considered part of the business of baseball. The Curt Flood Act was a Congressional mistake, the product of years of faulty analysis and absurd holdings by the Supreme Court. This note will explain how the exemption came to fruition, outline the various problems with its inception, and conclude by proposing that Major League Baseball should be subject to antitrust law, just like all other professional sports leagues

    π\pi-Electron Ferromagnetism in Metal Free Carbon Probed by Soft X-Ray Dichroism

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    Elemental carbon represents a fundamental building block of matter and the possibility of ferromagnetic order in carbon attracted widespread attention. However, the origin of magnetic order in such a light element is only poorly understood and has puzzled researchers. We present a spectromicroscopy study at room temperature of proton irradiated metal free carbon using the elemental and chemical specificity of x-ray magnetic circular dichroism (XMCD). We demonstrate that the magnetic order in the investigated system originates only from the carbon π\pi-electron system.Comment: 10 pages 3 color figure

    The role of hydrogen in room-temperature ferromagnetism at graphite surfaces

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    We present a x-ray dichroism study of graphite surfaces that addresses the origin and magnitude of ferromagnetism in metal-free carbon. We find that, in addition to carbon π\pi states, also hydrogen-mediated electronic states exhibit a net spin polarization with significant magnetic remanence at room temperature. The observed magnetism is restricted to the top ≈\approx10 nm of the irradiated sample where the actual magnetization reaches ≃15 \simeq 15 emu/g at room temperature. We prove that the ferromagnetism found in metal-free untreated graphite is intrinsic and has a similar origin as the one found in proton bombarded graphite.Comment: 10 pages, 5 figures, 1 table, submitted to New Journal of Physic

    Population Trends and Policies in the UNECE Region: Outcomes, Policies and Possibilities

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    With the 20-year anniversary of the landmark International Conference on Population and Development (ICPD) on the horizon, the UN General Assembly asked the UN Population Fund (UNFPA) to lead a global process aimed at taking stock of the progress that has been made in implementing the Programme of Action adopted by the ICPD in Cairo in 1994, and at identifying priorities for the future. In the region comprising Europe, Central Asia, North America and Israel, UNFPA, together with the UN Economic Commission for Europe (UNECE), initiated a comprehensive process of consultations with governments, civil society, academia, youth and parliamentarians to solicit their input and ideas for an updated population and development agenda for the 21st century

    Ab-initio study of the relation between electric polarization and electric field gradients in ferroelectrics

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    The hyperfine interaction between the quadrupole moment of atomic nuclei and the electric field gradient (EFG) provides information on the electronic charge distribution close to a given atomic site. In ferroelectric materials, the loss of inversion symmetry of the electronic charge distribution is necessary for the appearance of the electric polarization. We present first-principles density functional theory calculations of ferroelectrics such as BaTiO3, KNbO3, PbTiO3 and other oxides with perovskite structures, by focusing on both EFG tensors and polarization. We analyze the EFG tensor properties such as orientation and correlation between components and their link with electric polarization. This work supports previous studies of ferroelectric materials where a relation between EFG tensors and polarization was observed, which may be exploited to study ferroelectric order when standard techniques to measure polarization are not easily applied.Comment: 9 pages, 6 figures, 5 tables, corrected typos, as published in Phys. Rev.

    Experimental Evidence for Two-Dimensional Magnetic Order in Proton Bombarded Graphite

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    We have prepared magnetic graphite samples bombarded by protons at low temperatures and low fluences to attenuate the large thermal annealing produced during irradiation. An overall optimization of sample handling allowed us to find Curie temperatures Tc≳350 T_c \gtrsim 350 K at the used fluences. The magnetization versus temperature shows unequivocally a linear dependence, which can be interpreted as due to excitations of spin waves in a two dimensional Heisenberg model with a weak uniaxial anisotropy.Comment: 4 pages, 3 figure
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